title: Segmental spinal reflex adaptations associated with chronic ankle instability.
abstract: OBJECTIVE
  To further understanding of the role that segmental spinal reflexes play in chronic ankle instability (CAI).
  
  
  METHODS
  A 2 x 2 repeated-measures case-control factorial design. The independent variables were ankle group with 2 levels (healthy, CAI) and stance with 2 levels (single, double legged).
  
  
  METHODS
  University research laboratory.
  
  
  METHODS
  Twenty-two participants with CAI and 21 matched healthy controls volunteered.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  The dependent variables were 2 measures of motoneuron pool excitability: paired reflex depression (PRD) and recurrent inhibition.
  
  
  RESULTS
  A 2 x 2 repeated-measures multivariate analysis of variance revealed a significant interaction between group and stance on the linear combination of PRD and recurrent inhibition variables (Wilks lambda=.808, F(2,40)=4.77, P=.014). Follow-up univariate F tests revealed an interaction between group and stance on the PRD (F(1,41)=9.74, P=.003). Follow-up dependent t tests revealed a significant difference between single- and double-legged PRD in the healthy participants (t(20)=-3.76, P=.001) with no difference in CAI participants (t(21)=-0.44, P=.67). Finally, there was a significant difference in recurrent inhibition between healthy (mean, 83.66) and CAI (mean, 90.27) (P=.004).
  
  
  CONCLUSIONS
  This study revealed that, compared with healthy participants, CAI participants were less able to modulate PRD when going from a double- to a single-legged stance. Additionally, CAI participants showed higher overall levels of recurrent inhibition when compared with healthy matched controls.
authors.affiliation: Department of Kinesiology, Auburn University, Auburn, AL 36849-5323, USA. jmsefton@auburn.edu
authors.forename: JoEllen M
authors.initials: JM
authors.lastname: Sefton
authors.forename: Charlie A
authors.initials: CA
authors.lastname: Hicks-Little
authors.forename: Tricia J
authors.initials: TJ
authors.lastname: Hubbard
authors.forename: Mark G
authors.initials: MG
authors.lastname: Clemens
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Yengo
authors.forename: David M
authors.initials: DM
authors.lastname: Koceja
authors.forename: Mitchell L
authors.initials: ML
authors.lastname: Cordova
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D000704:Analysis of Variance; D000842:Ankle / Q000294:innervation / Q000502:physiology*; D016512:Ankle Injuries / Q000503:physiopathology*; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D013116:Spinal Cord / Q000502:physiology